Explore, through Lange’s granddaughter’s eyes, the life story of the influential “Migrant Mother” photographer. Never-before-seen photos and film footage reveal the artist who challenged America to know itself. Pictured: Probably Lange’s most recognized photograph is “Migrant Mother” of Florence Owens Thompson and her children in 1936 in Depression ravaged California. As Lange took the photograph, Thompson, 32, told of how they had been living on frozen vegetables in the surrounding fields and the birds that the children killed. She had just sold the tires from her car to buy food. Photo from the Library of Congress collection. “DOROTHEA LANGE Grab A Hunk of Lightning ” airs on AMERICAN MASTERS from PBS on Tuesday, March 21, at 7 PM on KTWU-HD, Digital Channel 11.1.